1. Field of the Invention
This invention pertains to treating subjects having a condition associated with excess weight comprising downregulating neural activity on the vagus nerve and administering a composition that alters the energy balance of the subject.
2. Background
Obesity and other eating disorders are serious health conditions that lead to increased morbidity and mortality. Over the last decade, the prevalence of obesity has increased more than 80%, representing an estimated 43 million adults in 2002. (Mokdad A H, et al, The spread of the obesity epidemic in the United States, 1991-1998. JAMA 1999; (282):1519-22) In terms of mortality, an estimated 280,000 to 325,000 adults in the United States die each year from causes related to obesity. (Allison D B et al, Annual deaths attributable to obesity in the United States. JAMA 1999; 282:1530-8) More importantly, excess weight has been positively correlated with years of life lost. (Fontaine K R et al., Years of life lost due to obesity. JAMA 2003; (289):187-93).
In addition to mortality, substantial morbidity is associated with obesity. For example, in 2000, the total cost of obesity in the United States was estimated to be $117 billion ($61 billion in direct medical costs, $56 billion in indirect costs). (U.S. Department of Health and Human Services. The Surgeon General's call to action to prevent and decrease overweight and obesity. Rockville, Md.: U.S. Department of Health and Human Services, Public Health Service, Office of the Surgeon General; 2001). An estimated 9.1% of annual medical spending in the United States is attributed to overweight and obesity—a figure that rivals medical costs attributable to cigarette smoking.
Treatments for overweight and/or obese patients include both non pharmaceutical and pharmaceutical treatments. Non pharmaceutical treatments include diet, exercise, nerve stimulation, nerve block, and surgical treatments. Pharmaceutical treatments include appetite suppressants, energy expenditure modifying agents, antidepressants, and uptake of nutrient inhibitors. Despite the existence of several treatments, the number of people that are obese or have other eating disorders as well as the costs associated with these conditions continue to rise.
A wide variety of disorders where the treatment includes blocking neural impulses on the vagus nerve have been described. Specific disorders treated include obesity and other eating disorders. Such treatments are described in commonly assigned U.S. Pat. No. 7,167,750 to Knudson et al. issued Jan. 23, 2007 and in the following commonly assigned U.S. patent applications: US 2005/0131485 A1 published Jun. 16, 2005, US 2005/0038484 A1 published Feb. 17, 2005, US 2004/0172088 A1 published Sep. 2, 2004, US 2004/0172085 A1 published Sep. 2, 2004, US 2004/0176812 A1 published Sep. 9, 2004 and US 2004/0172086 A1 published Sep. 2, 2004.
Since 1995, several agents have been available for treatment of obesity and other eating disorders. However, in the case of obesity, the amount of weight lost has been modest even with long term treatment. In addition, several of the agents are known to have serious side effects at the doses that are effective for weight loss. For example, fenfluramine and dexfenfluramine were withdrawn from the market due to a reported association between administration of these drugs and valvular heart disease. Clinical Guidelines of the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. NIH Publication No. 98-4083, September 1998.
Thus, there remains a need to develop effective treatments for conditions associated with excess weight.